| Intrusive breccias can be the host for metallic ore deposits and aesthetic mineral specimens. |
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| They consist of intrusive materials, breccias, tuffs and massive peripheral lava flows. |
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| These eruptions deposited pebble-grade volcaniclastic breccias of an intermediate composition within a few kilometres of the Rio Tinto Anticline. |
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| Howardites are polymict breccias composed of angular clasts of eucrites and diogenites welded together by pulverized mineral dust. |
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| Galena is also found as larger isolated octahedral crystals within the coarse calcite cement in breccias in the upper parts of the core. |
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| Massive dolomite and dolomitic breccias are separated by a normal fault from the upper part of the sequence. |
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| Breccias are associated with mechanical weathering in regions of high tectonic activity. |
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| Basement rocks consist of Tortonian volcanic rocks unconformably overlain by Messinian marine marls, coral-reef limestones and carbonate breccias. |
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| In these types of deposits, gold and silver are precipitated by hot springs in fissures, faults, and explosive breccias in the upper portions of the mineral system. |
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| The mafic sheets have not contributed at all to the felsic volcanic-derived volcaniclastic breccias, thus supporting an intrusive origin for the mafic volcanic rocks. |
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| Numerous southwest-trending, high-angle fracture zones and breccias cut the 250-foot wide by 600-foot long mineralized zone. |
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| In some sedimentary breccias, termed 'granite conglomerate', they are the dominant clast type. |
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| These mineralized intercepts occur in zones of potassic altered diatreme breccias. |
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| At depth, some kimberlite breccias grade into root zones of dikes made of unfragmented rock. |
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| To the west the Round Hows are examples of bedded breccias sandstone and tuffs. |
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| The caves are enlarged out of Lower Permian sandstones and their associated breccias and purple shales. |
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| Vent facies on the north and eastern sides of Fish Lake are mostly flows and breccias of andesite and rhyodacite. |
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| Mineralization is associated with siderite-albite veins and breccias with chalcopyrite, arsenopyrite, pyrite, and their oxidized equivalents. |
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| The pebbly sandstone and breccias of the Pavey Ark Member also cross the fell. |
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| The breccias are composed of fragments of altered, angular tuff fragments cemented with an intergrowth of tourmaline and quartz. |
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| The gold mineralization is related to quartz-pyrite replacement along bedding and foliation planes and in breccias. |
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| Conglomerates are dominantly composed of rounded gravel, while breccias are composed of dominantly angular gravel. |
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| Most samples indicated widespread hydrothermal alteration consisting of argillic and potassic alteration and the formation of extensive quartz breccias. |
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| In addition, how could slickensides, fault gouge and breccias, and the sharply offset rock layers along faults have formed in rock that was still soft? |
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| The northern crags expose some granophyric granite of the Ennerdale Intrusion, together with the bedded breccias, sandstones and tuffs of the Round How Member. |
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| This fourth miscellaneous category includes rocks formed by Pyroclastic flows, impact breccias, volcanic breccias, and other relatively uncommon processes. |
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